Tech Analysis: Halo 3: ODST

The recent arrival of Halo 3: ODST brought Microsoft's tentpole franchise back to the forefront, and collected another impressive 8/10 from Eurogamer, despite the fact the game was sculpted from scratch in just 14 months by a Bungie team left project-less after the much-vaunted Peter Jackson collaboration crashed and burned.

In the wake of the ODST's premiere at E3 this year, we talked about the game's possibilities based on the available media, combined with in-depth knowledge of the Halo 3 engine, backed up with a range of performance metrics based on the existing game. We speculated on how the existing tech could be repurposed to produce a game undoubtedly inferior technologically to Guerrilla Games' Killzone 2, but competitive in other respects, by playing up to the engine's core strengths uncopied by the competition.

Killzone 2 is a beast of a game with a graphical engine that exerts a huge amount of the PS3's raw power, to the point where even its hardware limitations are taken into account, and integrated into the game's artistic look and the engine's overall performance. The Halo 3 tech on the other hand is all about versatility. It can do the more usual FPS corridor shooting (though the results don't tend to look state-of-the-art), but it really comes into its own with vast, open levels and numerous intelligent AI presences. In order to be competitive with the best of the rest, Bungie needed to think smart, leveraging its existing tech with minimal upgrades. The result is a first class shooting game state-of-the-art in many ways, but never freeing itself from the shackles of what is basically the firm's three-year-old technology.

Originally announced as an expansion pack before it was upped to full retail status with a bonus multiplayer disc, ODST's origins are reflected in the final size of the actual game code. Disc one installs in its entirety to your Xbox 360 hard disk and consumes a mere 3.5GB of space, up against the nigh-on 3.2GB of the second multiplayer disc. In terms of basic data storage, this could have been a single DVD product, but this could have caused issues in terms Achievement allocations, plus of course there's the additional marketing value of releasing a two-disc package.

Over and above that, a hard disk install install does improve performance on the ODST campaign side of things, in contrast to Halo 3, where streaming data from the hard disk added significantly to the loading times. However, the advantage is nullified on the "legacy" multiplayer disc, which still runs more speedily from the DVD.

Returning to the core technology at work in ODST, the basic limitations of Halo 3's engine are not resolved. It's still rendering at 1152x640 and it still has no anti-aliasing. Levels sometimes feel lacking in geometry, making those jagged edges stand out even more than they should. The wide open areas we predicted did make it in to the game to various extents, but this comes with a cost. The further away an object is, the fewer pixels it has available for its definition, and the more impact the sub-HD resolution has on the overall image quality.

The fact that most of the game is set at night-time mitigates this somewhat, as does the inclusion of a grain filter, which works with the motion blur, ramped-up HDR and bloom to produce a relatively smoother effect. Bungie's SIGGRAPH 09 presentation reveals that the firm has a good grip on time-of-day lighting and emulating atmospheric conditions within the engine (something we expect to see expanded upon in Halo: Reach) and this manifests itself in ODST: muted colour schemes and interesting use of layered alpha textures (i.e. smoke) also helps in smoothing off the scene.

With one or two exceptions, the overall look of the game in terms of setting and lighting works well in disguising limitations inherent in the Halo 3 engine.

However, the daytime scenes, including the game's climax, inadvertently showcase the resolution limitations in a fashion that undoes a lot of the good work elsewhere. The look is harsh and undetailed. Were it not for the sheer volume of opponents being thrown your way, the overall appearance of some of these scenes would feel last-generation, even. While there is evidence that the texture filtering and alpha draw distance has been improved (grass doesn't just appear out of nowhere now), it's still not fantastic, and shadow draw distance remains disappointing.

We were expecting ODST to play to the engine's strengths in terms of open battle arenas with a large amount of opponents, but the concept of the game with its enclosed cityscapes doesn't generally lend itself to this sort of arrangement. In truth, it's in Halo 3 where we see this to its fullest extent and perhaps the best example of what Bungie is capable of while maintaining a solid frame-rate with the current tech.

However, the new city environment in ODST does have an interesting effect on the Bungie AI. This is one element of the Halo tech that remains state-of-the-art, and while it hasn't seen much improvement in ODST, it's almost as if the new setting lets the AI code "breathe" more, with more of its potential realised even on the default difficulty level.

While AI in ODST is much the same tech-wise as that found in Halo 3, the new environments bring about different behaviours during combat.

This subtle alteration in AI behaviour is perhaps more evident towards the end of the game, where the Brutes react differently or even retreat depending on the weapons you're deploying against them. In Halo 3, most of the open levels were vehicle-based, and as such, you didn't feel as though the AI had as much room to manoeuvre when compared with the up-close and personal combat that is the core essence of ODST. Over and above that, the very make-up of the city levels themselves opens up more behaviour avenues for the AI, due to the additional cover offered.